This invention relates to a cable switch, more particularly to an omnidirectionally responsive cable switch capable of being wired or laid on a required position in a snake-like or twisted manner.
Cable switches are already described in the official gazettes of Japanese Utility Model Laid-Open Publication No. 77033 as shown in FIG. 16, Japanese Utility Model Laid-Open Publication No. 77035 as shown in FIG. 17 and Japanese Patent Laid-Open Publication No. 5190055 as shown in FIG. 18, respectively of the accompanying drawings.
The Japanese Laid Open Utility Model Publication No. 77033 comprises a restorable tubular cable member 14, two pieces of conductive rubber 12, 12 serving as a contact member, two narrow belt like flat nets of electric wires 11a, 11b respectively contained in the conductive rubbers 12, 12 and an air gap 13 formed between the conductive rubbers 12, 12.
The Japanese Laid Open Utility Model Publication No. 77035 comprises a restorable cable member 26, an upper bridging electric conductor 24, lower conductive rubbers 22, 22 fixed on the inner surface of the cable member 26 and spaced apart from each other by means of a longitudinal central supporting protrusion 25, and two narrow belt-like flat net of electric wires 21a, 21b respectively contained in the conductive rubbers 22, 22.
The Japanese Laid Open Patent Publication No. 190055/1993 comprises a tubular insulating member 35, two narrow belt-like cores 31, 31 inserted in the insulating member 35 while leaving an air gap 34 therebetween and two electric wires 32a, 32a respectively wound on the belt-like cores 31, 31.
These cable switches can be actuated only under substantial compressive pressure in the vertical direction but can not respond to pressure in the horizontal direction owing to their construction.
Further, owing to the same reason, the Japanese Laid Open Utility Model Publication No. 7-7033 is difficult to vertically bend for the purpose of wiring or laying on a required position, while the Japanese Laid Open Utility Model Publication No. 7-7035 and Japanese laid Open Patent Publication No 5-190055 are difficult to be horizontally bent for the same purpose.
Of late, with the development of a nursing robot and the like, it has been required to use such a cable switch that is gentle to patients or invalid persons and can be easily bent omnidirectionally for wiring or laying on the arm or hand of the robot while enabling it to omnidirectionally respond to substantial compressive pressure applied thereto at any point on the cable surface.
The omnidirectionally responsive cable switch can be used, for example, in the site of road construction, maintenance and other works and in such cases where it is often required that the switch be further protected or guarded against possible damage of the embedded conductive rubbers due to violent pull and the like.